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MGS geologists presented talks at the 2015 Maryland Water Monitoring Council Annual Conference, November 13, 2015

Occurrence of Elevated Radioactivity in the Upper and Lower Patapsco Aquifers in Charles County, Maryland

David Andreasen (Co-author: David Bolton)

ABSTRACT

Five public-water supply systems in Charles County that obtain water from the Upper and Lower Patapsco aquifers exceeded the USEPA’s Maximum Contaminant Level (MCL) of 15 picocuries per liter (pCi/L) for gross-alpha particle activity (GAPA). Polonium-210 was detected in two of these water systems. Radium-226 plus radium-228 concentrations were all below the MCL of 5 pCi/L. GAPA levels in eleven other Charles County water systems in these aquifers were between 10 and 15 pCi/L. To determine whether the radioactivity is localized in specific zones within these aquifers, Maryland Geological Survey personnel compiled existing water-quality and well-construction data from the affected water-supply systems. The presence of multiple screened intervals in the wells, as well as inconsistencies and variability in data reporting, hampered determination of vertical distribution of radioactivity within the aquifers. Additional sampling is recommended for private water-supply wells near the affected public water systems. These wells typically have screened-interval lengths of ten feet or less, which will make them useful in locating source of radioactivity within the stratigraphic section.

Johanna Gemperline (Co-author: David Andreasen)

ABSTRACT

Periodic maintenance dredging is required to maintain adequate depths in the Port of Baltimore shipping channels. The Maryland Port Administration, seeking to increase future storage capacity for dredged material, has recently proposed the addition or expansion of facilities at the Masonville vessel birth and the Cox Creek Dredged Material Containment Facility. The placement of dredged material at both sites has the potential to affect the Lower Patapsco and Patuxent aquifer systems, which are major sources of drinking water for Anne Arundel County. The Maryland Geological Survey conducted studies in 2014 and 2015 to determine the likelihood of groundwater contamination or flow change at these sites. Using lithologic logs, geophysical logs, and groundwater levels, the studies concluded that the direction of groundwater flow and effectiveness of confining units prevent contamination of the aquifer systems.

Groundwater Sustainability in Maryland's Coastal Plain Province

Andrew Staley

ABSTRACT

Groundwater is nearly the sole source of fresh drinking water for approximately 1.4 million people living in Maryland's Coastal Plain. A sustainable supply of clean drinking water is crucial to the health and well-being of the citizens of Maryland, in addition to a strong economic future for the State. Aside from being the dominant drinking water source, groundwater is also important for irrigation, commercial and industrial uses, and power plants. And because groundwater interacts with streams and wetlands, it also plays a vitally important role in sustaining healthy populations of fish and other aquatic organisms. Groundwater in the Coastal Plain of Maryland occurs in at least 15 regional aquifer systems, each possessing a unique hydrogeology with a variety of challenges to sustainable use. In certain areas of the Coastal Plain groundwater supply may be severely constrained in the future as a result of overuse of the aquifers and poor water quality, while in other areas groundwater supply is robust and sustainable. In this talk, concepts of groundwater sustainability will be discussed and case studies illustrating both sustainable and non-sustainable groundwater supplies will be presented.